Microscope



L. H. BROWN 2,156,911

MICROSCOPE May 2, 1939.

Original Filed Oct. 5, 1935 2 Sheets-Sheet l Fig: 2

INVENTOR L 490 h. firo wn 74A? ATTORNEY.

y 2, 1939- L. H. BROWN 2,156,911

MICROSCOPE Original Filed Oct. 5, 1955 2 Sheets-Sheet 2 INVENTOR. Leo H Brown 7M ATTORNEY.

Patented May 2, 1939 I 2,156,911

UNITED STATES PATENT OFFICE MICROSCOPE Leo H. Brown, Nea York, N. Y.,

- Rcflled for abandoned application Serial No.

43,765, October 5, 1935. This application November 6, 1937, Serial No. 173,109

2 Claims. (01. 88-39) This invention relates to microscopes and parparticularly to Figs. 1 and 2, the microscop in ticularly, to the objective therefor, this applicacomp ses e ye Pieee 3 the Objective e tion being refiled for my abandoned application, stage l3, and the arm I4 carrying the stage l3 Serial No. 43,765, filed October 5th, 1935. at one end, and at its other end supporting the o In microscope objectives commonly used, light tube 24 c rry n h ey p c n objective- 5 passes through the transparent lens or lenses of The arm as is u a s p v e s a l5 t0 the objective with attendant objectionable the base Meens a P v d o dj s chromatic aberration. Various combinations of the distance 0f the Objective and the y Piece lenses have been employed to avoid such aberra- II as a unit from the sta e s id means 00mtion but such combinations are expensive and prising the ck on the supporting tube 24 10 never eliminate all chromatic aberration. the eye Piece and j c e, a t e P o The so-called achromatic" objective corrects pivoted 0n the arm and Operated y the only the primary spectrum, while the apochr thumb wheel 19. The usual illuminating mirror matic" objective, which represents the most ad- 29 is provided for directing light through a s e vanced microscope objective available at present, bearing the Object 0 t s ge 3 a d nto t e 15 corrects the primary'and secondary spectrums Objective 'without correcting the tertiary spectrum. Said objective I? is shOWn in d a in F My invention contemplates the provision of, a It comprises the tubular pp 22 t e ded as microscope objective employing mirror including at 23 at its upper end for insertion into the lower 2-,) a curved mirror, whereby the light from the obend 0f the mieleseepe tube In the o ject does not pass through any lens to form 2. Shown, a central Opening as is made in the spectrum, but is reflected, thereby completely tube 22, the pp end of the Opening being P- avoiding chromatic aberration and resulting in tiohelly Closed if desired y the thin glass Plate an inexpensive achromatic magnifying objective. 25 to keep dust and circulating out of h My invention further contemplates t proviobjective and thereby to prolong the life of the 25 sion of a microscope objective employing a comreflecting surfeeee- The lower 001110841 Py paratively small r d reflecting t magnifydal surface 21 of the tube 22 is at such an angle ing surface which may b i th form of to the axis of the tube as to permit the concave cave ellipsoid of revolution or 'any other curve reflecting mirror 23 to be secured thereto t the approximating such ellipsoid, and designed to be proper angle to reflect the light f the O je 30 focused on an object close to the objective to to the Seeond mirror 29, Whieh in turn reflects creat a magnified image capable of being again the light through the opening 25 and the tube 24, magnified by the eye piece of the microscope. the mirror 28 focusing the image in t ye P e e The various objects of my invention will be h mirror 29 is Opposite the Opening clear from the description which follows, and While the mirror 23 is Opposite the Opening 5. 35

from the drawing i hi h, said openings being relatively ofiset or out of Fig. 1 is a side elevation, partly in vertical secali t Wit each other. tion, of a microscope to which my invention has The Operative surface of a d m ro 8 s a b n applied 7 surface of revolution and while theoretically an 4 Fig. 2 i a, vertical section of ne f r of my ellipsoid of revolution, I have found that for new bjecti practical purposes; the surface may be spherical Fig. 3 is a vertical section of a modified form of or y regular su a of v ut ppr x the objective. mating the ellipsoid. Spherical surfaces are Fig. 4 is a diagrammatic view of another modicomparatively y to grind d p oduce 0 mfied form of the objective. merically, and serve the purpose of magnification 45 Fig 5 i a diagrammatic ti similar t sufiiciently well for commercial and laboratory Fig. 4 of a microscope to which my invention has the errors, if resulting from the difbeen applied howing h magnification occurs ference between the theoretically correct ellip- Fig. 6 is a vertical section of another modified soidal surface and the spher surface being form of my new objective wherein t o u ved unimportant, particularly when compared to the 50 I mirrors are used to reduce the curvature of the h y desirable a t ges of the resulting comreflecting mirrors. pletely achromatic but inexpensive objective. In the practical embodiment of my invention, Furthermore, the area of the reflecting surface wherein my new objective replaces the objective being only a small fraction of that of the entire 5 customarily used in microscopes, and referring sphere from which it is derived, the variation in curvature from the theoretically correct ellipsoid is so small that the use of the spherical reflecting surface in the objective causes no material error. As is well understood, two focii are present in the theoretically correct ellipsoid, the

objectbeing theoretically placed at one focus of the ellipsoid and the, image being thereby focussed at the other focus of the ellipsoid. In practice, however, the object is not arranged at the center of the spherical surface of the mirror (Fig. 5). It is instead arranged preferably between the mirror 28 and the center of curvature of its reflecting surface. It is the ofl center arrangement of the object which causes magnification. The diameter of the image is proportional to its distance from the mirror 28. If it is three times as far from the mirror as the object is, then the image has a diameter three times that of the object. The image focused by the mirror 28 in the eye piece II, is again magnifled by the eye piece, the amount of the magniflcation being variable by adjusting the eye piece in the usual manner.

The mirror 28 may be silvered on its concave reflecting surface and may be made of glass or other suitable material and is secured to the surface 21 of the tube 22 by any suitable means such as the cement 3|. At its lower end said tube is threaded as at 32 for engagement with corresponding threads of the second tube 33. The plane mirror 29 is suitably cemented to the preferably inclined interior surface 36 near the bottom of said tube and in the proper position to receive the light reflected by the mirror 28 thereon and to reflect said light through the opening 25 to the eye piece. Said second tube 33 is provided with a suitable opening 35 through which the light from the object 36 passes and impinges upon the mirror 28. The glass plate 31 may be used optionally to close the opening 35 against the entrance of dust or air into the interior of the tube 33.

In that form of my invention shown in Fig. 3,

the opening 40 of the tube fill is made centrally in said tube instead of at one side, but the opening 42 in the upper tube 43 thereby becomes arranged non-centrally of the latter tube. This arrangement is more suitable for amateurs who are accustomed to have the light entrance opening of theobjective arranged centrally. In the form shown, the concave mirror 28 is cemented at its proper angle to the bottom 65 of the tube d3 by suitable cement'45.

Referring to the diagrammatic view shown in Fig. 4, the light from the object first strikes the spherical surface 46 of the mirror 61, being reflected thereby to the plane mirror 38, then on to the plane mirror 49 and then into the objective. The mirror 61 is arranged on one side of the microscope tube axis and is provided with a shield 50 extending transversely past said axis and preventing light from entering directly into the tube. It will be noted that the adjacent lower ends of the mirrors t8 and 69 are spaced apart suificiently to permit the light from the object 30 to reach the reflecting surface 66 and that the light is directed by the mirror $9 in the same general direction as the light from the object 30 to the surface 56.

In order to reduce the cost of grinding and the cost of the spherical or ellipsoidal mirrors, the plane mirror 29 or the plane mirrors 68 and 49 may be replaced by one or more concave mirrors. This has been illustrated in that form of my invention shown in Fig. 6 wherein the mirror 5|,

*' one spherical or the likeconcave reflecting surface in connection with another reflecting surface, but using no lenses, whereby chromatic aberration is completely eliminated, that the refleeting surface may be spherical without material error over the theoretically correct ellipsoidal surface and that I have produced a microscope objective well designed to meet the requirements of practical use.

While it has been suggested that curved reflecting surfaces or mirrors be used in telescopes, I am not aware of any previous suggestion that such surfaces could be used to replace the lenses in microscope objectives, nor is it possible to use spherical reflecting surfaces in telescopes. Curved reflecting surfaces when used in telescope objectives do not magnify as they must in microscopes. Furthermore, in telescopes, there can be no variation of power for a given objective In microscopes, however, the

and eye piece. power may be varied by varying the distance between the eye piece and the objective. The curvature of the lenses have diflerent eflects in telescopes and microscopes. In the former, the

greater the curvature, the less the power, wherefunctions in a different manner, particularly, since the telescope objective does not magnify and the microscope objective must in order to function properly.

While I have shown and described certain specific embodiments of my invention, I do not wish to be understood as limiting myself thereto, but

intend to claim the invention as broadly as may be permitted by the state of the prior art and the scope of the appended claims.

I claim: 1

1. In a microscope, an eye-piece-supporting and objective-supporting tube, an adjustable eye piece at one end of the tube, a cylindrical member removably screwed into the other end of the tube and having a longitudinally extending opening therein, the axis of the opening being parallel to the axis of the tube, a tubular member screwed to the cylindrical member and having a mirror chamber therein, said tubular member being closed at its end remote from the cylindrical member and having a longitudinal opening at said end, the axesof said openings being in substantially parallel spaced relation to each other, the combined lengths of the cylindrical and tubular members being less than the length of said tube, a first spherically concave mirror supported within the chamber adjacent the cylindrical member and arranged substantially vertically above the opening in the tubular member with its reflecting surface inclined to the axis of and facing the opening in the tubular mem- Ill) ber, a second mirror in the chamber adjacent the closed end of the tubular member and substantially vertically below the opening of the cylindrical member and arranged with its reflecting surface inclined to the axis of the opening in the cylindrical member and facing the reflecting surface of the first mirror, a microscope frame including a stand, a stage carried by the frame below the supporting tube, and cooperating means on the frame and the supporting tube for adjusting the closed end of the tubular member to a position closely adjacent the stage and to arrange an object on the stage in a position offset slightly from the center of the spherical surface of said first mirror.

2. In a compound microscope, an eye-piecesupporting and objective-supporting tube, an adjustable eye piece at one end of the tube, a first member removably attached to the other end of the tube and having an opening therein, a hollow member attached to the first member and having a mirror chamber therein, said hollow member having an opening therein at its end remote from the first member, the combined lengths of the first and hollow members being less than the length of the tube, a first mirror supported within the chamber adjacent the first member and facing the opening in the hollow member, a second mirror in the chamber adjacent the outer end of thehollow member and facing the opening of the first member and also facing the reflecting surface of the first mirror, at least one of said mirrors having a concave reflecting surface, a microscope frame including a stand, a stage carried by the frame below the supporting tube and cooperating means on the frame and the supporting tube for adjusting the outer end of the hollow member to a position closely adjacent the stage.

' LEO H. BROWN. 

